Method and System for Bi-Level Treatment of Sleep Apnea

ABSTRACT

A positive airway pressure device is disclosed herein. The positive airway pressure device includes a blower, a buffer chamber, a gas manifold, a first sensor, a second sensor, and a controller. The buffer chamber is downstream of the blower. The buffer chamber configured to receive gas generated by the blower and output the gas to a patient. The gas manifold is fluidly coupling the blower to the buffer chamber. The first sensor is at least partially disposed in the gas manifold. The first sensor is configured to measure a first pressure in the gas manifold. The second sensor is at least partially disposed in the buffer chamber. The second sensor is configured to measure a second sensor in the buffer chamber.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application Ser.No. 63/292,288, filed Dec. 21, 2021, which is hereby incorporated byreference in its entirety.

FIELD OF DISCLOSURE

The present disclosure generally relates to a positive airway pressuresystem, and more specifically, to a system and method for deliveringbi-level treatment to a patient using a positive airway pressure system

BACKGROUND

Non-invasive ventilation (NIV) is often used for patients experiencingrespiratory destress. This may be prescribed for patients withObstructive Sleep Apnea (OSA), Chronic obstructive pulmonary disorder(COPD), pneumonia or other respiratory disorders. NIV is oftenprescribed as supplying positive air pressure (PAP) to the patient by aface mask or other device such as nasal pillows. Depending upon thesymptoms, the PAP may be either continuous positive air pressure (CPAP)or bi-level positive air pressure.

SUMMARY

In some embodiments, a positive airway pressure device is disclosedherein. The positive airway pressure device includes a blower, a bufferchamber, a gas manifold, a first sensor, a second sensor, and acontroller. The buffer chamber is downstream of the blower. The bufferchamber is configured to receive gas generated by the blower and outputthe gas to a patient. The gas manifold fluidly couples the blower to thebuffer chamber. The first sensor is at least partially disposed in thegas manifold. The first sensor is configured to measure a first pressurein the gas manifold. The second sensor is at least partially disposed inthe buffer chamber. The second sensor is configured to measure a secondpressure in the buffer chamber. The controller is in communication withthe blower, the first sensor, and the second sensor. The controller isconfigured to perform operations. The operations include initializingthe blower to deliver a therapy pressure to the patient during aninhale. The operations further include receiving, from the secondsensor, real-time pressure readings while delivering therapy to thepatient. The operations further include analyzing the real-time pressurereadings to determine that the patient is about to switch from theinhale to an exhale. The operations further include, based on theanalyzing, causing the blower to deliver an expiratory pressure to thepatient during the exhale. The expiratory pressure is a lower pressurethan the therapy pressure.

In some embodiments, a method of delivering therapy to a patient using apositive airway pressure device is disclosed herein. A computing systeminitializes a blower of the positive airway pressure device to deliver atherapy pressure to a patient during an inhale. The computing systemreceives, from a second sensor positioned at least partially in a bufferchamber of the positive airway pressure device, real-time pressurereadings while delivering therapy to the patient. The computing systemanalyzes the real-time pressure readings to determine that the patientis about to switch from the inhale to an exhale. Based on the analyzing,the computing system causes the blower to deliver an expiratory pressureto the patient during the exhale. The expiratory pressure is a lowerpressure than the therapy pressure.

In some embodiments, a positive airway pressure device is disclosedherein. The positive airway pressure device includes a blower, a bufferchamber, a gas manifold, a first sensor, a second sensor, and acontroller. The buffer chamber is downstream of the blower. The bufferchamber is configured to receive gas generated by the blower and outputthe gas to a patient. The gas manifold fluidly couples the blower to thebuffer chamber. The first sensor is at least partially disposed in thegas manifold. The first sensor is configured to measure a first pressurein the gas manifold. The second sensor is at least partially disposed inthe buffer chamber. The second sensor is configured to measure a secondsensor in the buffer chamber. The controller is in communication withthe blower, the first sensor, and the second sensor. The controller isconfigured to perform operations. The operations include initiating acalibration process for the first sensor. The calibration processconfigured to reduce differences in readings between the first sensorand the second sensor. The operations further include recording a firstplurality of pressure readings from the first sensor and a secondplurality of pressure readings from the second sensor. The firstplurality of pressure readings and the second plurality of pressurereadings are based on a varying amount of pressure delivered to thepositive airway pressure device. The operations further includecorrelating the first plurality of pressure readings with the secondplurality of pressure readings. The operations further includecalibrating the first sensor based on the correlating.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrated onlytypical embodiments of this disclosure and are therefore not to beconsidered limiting of its scope, for the disclosure may admit to otherequally effective embodiments.

FIG. 1 is a block diagram illustrating a positive airway pressure (PAP)device with interface to a patient, according to example embodiments.

FIG. 2A illustrates a buffer chamber for use with the PAP device of FIG.1 , according to example embodiments.

FIG. 2B illustrates a buffer chamber for use with the PAP device of FIG.1 , according to example embodiments.

FIG. 2C illustrates a buffer chamber for use with the PAP device of FIG.1 , according to example embodiments.

FIG. 2D illustrates a buffer chamber for use with the PAP device of FIG.1 , according to example embodiments.

FIG. 3 is a chart illustrating patient respiratory response measured byfirst sensor, according to example embodiments.

FIG. 4 is a chart illustrating patient respiratory response measured bysecond sensor, according to example embodiments.

FIG. 5 is a chart illustrating portion of the chart of FIG. 4 in moredetail, according to example embodiments.

FIG. 6 illustrates an example how first sensor of PAP device may becalibrated, according to example embodiments.

FIG. 7 is a flow diagram illustrating a method of administering therapywith PAP device, according to example embodiments.

FIG. 8 is a flow diagram illustrating a method of administering therapywith PAP device, according to example embodiments.

FIG. 9A is a block diagram illustrating a computing device, according toexample embodiments.

FIG. 9B is a block diagram illustrating a computing device, according toexample embodiments.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements disclosed in oneembodiment may be beneficially utilized on other embodiments withoutspecific recitation.

DETAILED DESCRIPTION

During CPAP ventilation, a continuous flow of air is supplied to thepatient. The typical range of the applied pressure is between 4 and 20centimeters of water pressure (cm H₂O) During bi-level ventilation thepressure is changed between inspiration and expiration so that thepressure is higher during inspiration and then lower during expiration.

During bi-level ventilation for spontaneously breathing patients, it isimportant for the NIV device to automatically sense when the patientends their inspiratory cycle and begins expiration. Likewise, it isimportant for the device to sense the end of the patient's expirationcycle and begins inspiration. Therefore, it is important toalgorithmically determine a threshold to instruct, trigger, the deviceto switch between inspiration and expiration pressures.

During CPAP ventilation some patients find that exhaling against thefull pressure of the device is uncomfortable and that it is desirable tolower the pressure during expiration and increase it during inspiration.As with bi-level therapy, the device needs to apply thresholds so thatswitching between inspiration and expiration pressures occursautomatically.

One or more techniques described herein provides an improvement overconventional system by providing methods for determining the patientspecific trigger thresholds for automatically switching betweeninspiration and expiration pressures for spontaneously breathingpatients using PAP devices.

FIG. 1 is a block diagram illustrating a positive airway pressure (PAP)device 100 with interface to a patient 101, according to exampleembodiments. As shown, PAP device 100 may include a body 102 defining aninterior volume 104. PAP device 100 may include a blower 106, a gasmanifold 108, a buffer chamber 110, a connector 112, and amicroprocessor 114 disposed in interior volume 104.

Blower 106 may be configured to deliver air to gas manifold 108. Blower106 may include a blower controller 116 associated therewith. Blowercontroller 116 may be configured to control operation of blower 106. Forexample, blower controller 116 may be configured to provide electricalinput to blower 106 to control a speed of blower 106. For example,blower controller 116 may provide blower 106 with electrical input toobtain a setpoint pressure. In some embodiments, blower controller 116may provide electrical input to blower terminal block 118 to controlspeed of blower 106. The speed of blower 106 may be directly related tothe maintained pressure.

Gas manifold 108 may be configured to fluidly couple blower 106 withbuffer chamber 110. Buffer chamber 110 may be configured to maintain avolume of gas that is removed from blower 106. For example, gas may flowfrom blower 106, through gas manifold 108, and into buffer chamber 110.

Connector 112 may be configured to couple buffer chamber 110 with gasmanifold 108. Connector 112 may provide a flow channel from gas manifold108 to buffer chamber 110. As shown, in some embodiments, connector 112may include check valve 120. Check valve 120 may be representative of aone-way valve or gate configured to prevent backflow of gas into blower106. For example, check valve 120 may be configured to prevent gas athigher pressure from flowing back into blower 106 from buffer chamber110. If, for example, blower 106 is turned off, check valve 120 may beconfigured to prevent air from escaping back through blower 106. Suchprevention may result in a more consistent control of the deliveredpressure and may reduce influence from a patient's respiratory response.In some embodiments, check valve 120 may be designed such that, whenblower 106 is turned off, check valve 120 may open a path to externalair. Such functionality may ensure that the patient is not asphyxiatedin the case of a power failure.

As shown, PAP device 100 may further include a patient connection port122. Patient connection port 122 may be configured to output gas to apatient delivery system 124. For example, patient connection port 122may be representative of a port in communication with buffer chamber110. In operation, patient delivery system 124 may be detachably coupledto PAP device 100. Patient delivery system 124 may be representative oftubing that delivers gas to patient 101 via patient interface 126 (e.g.,mask).

PAP device 100 may further include a first sensor 130 and a secondsensor 132. First sensor 130 may be positioned proximate blower 106. Insome embodiments, such as that shown, first sensor 130 may be at leastpartially disposed in gas manifold 108. In some embodiments, firstsensor 130 may be at least partially disposed in blower 106. Generally,first sensor 130 may be disposed such that it is in close proximity toblower 106. First sensor 130 may be configured to monitor pressure andprovide feedback to blower controller 116 such that blower controller116 can maintain a set pressure. For example, first sensor 130 may sendto blower controller 116 a control signal that represents a measuredpressured in gas manifold 108. If the setpoint pressure differs from thecontrol signal pressure, blower controller 116 may increase or decreasethe speed of blower 106 to maintain the setpoint pressure. In thismanner, blower controller 116 may work in conjunction with first sensor130 to provide a feedback loop for maintaining a desired level ofpressure.

Second sensor 132 may be configured to monitor the patient's 101respiratory cycle. For example, as shown, second sensor 132 may be atleast partially disposed in buffer chamber 110. Generally, second sensor132 may be spaced from first sensor 130. For example, first sensor 130may be positioned on a first side of connector 112 and second sensor 132may be positioned on a second side of connector 112. Because secondsensor 132 may be configured to monitor pressure that is more directlyrelated to the respiratory response of patient 101, second sensor 132may inherently be more variable than first sensor 130.

First sensor 130 and second sensor 132 may indicate different pressuresdepending on the gas flow rate. For example, at a rate of 0.0 l/min (noflow), the difference between first sensor 130 and second sensor 132 iszero. As the flow rate increases, e.g., to 25 l/min, the differencebetween first sensor 130 and second sensor 132 becomes greater. For thisreason, it is useful to calibrate first sensor 130 and second sensor 132so that they are consistent at any flow rate (e.g., when a patient isspontaneously breathing at a fixed PAP, the average pressures for agiven number breathing cycles or for a specified time are the same forfirst sensor 130 and second sensor 132).

Microprocessor 114 may be configured to control operation of PAP device100. For example, microprocessor 114 may be configured to control thepressure setpoint of blower 106. In some embodiments, the initial setpoint of blower 106 may be referred to as the therapy pressure. Thetherapy pressure may be set by the user or automatically determined bymicroprocessor 114. The therapy pressure may be delivered to patient 101when patient 101 inspires.

As those skilled in the art understand, it is often difficult forpatients to expire against the therapy pressure. To account for this,microprocessor 114 can dynamically control the pressure delivered topatient 101 during use of PAP device 100. Microprocessor 114 maydynamically control the pressure by detecting the inspiration/expirationcycles of patient 101.

As shown, microprocessor 114 may be in communication with first sensor130 and/or second sensor 132. In operation, microprocessor 114 may beconfigured to analyze the patient's 101 respiratory cycle based on datafrom second sensor 132. For example, microprocessor 114 may use datafrom second sensor 132 to determine when patient's 101 expiration endsand inspiration begins (upper threshold), and when inspiration ends andexpiration begins. In this manner, microprocessor 114 can dynamicallyadjust the pressure pushing back against patient 101 when patient 101expires to provide the user with an easier expiration (i.e., patient 101is not expiring against full pressure). The pressure to which bloweroutput is set when patient 101 is expiring may be referred to as theexpiratory pressure. The change between the therapy pressure and theexpiratory pressure may be referred to as the pressure drop.

Microprocessor 114 may be configured to receive data from second sensor132. The data may be presentative of patient's 101 respiratory response.In some embodiments, the data from second sensor 132 is digital and canbe interpreted directly by microprocessor 114. In some embodiments, thedata from second sensor 132 is analog, in which case microprocessor 114may convert the analog signal to a digital signal before analysis. Basedon the received data, microprocessor 114 may applying one or moretechniques to determine if patient 101 is inhaling or exhaling. Ifinhaling, for example, the data indicates that the lower threshold ismet, thus signaling to microprocessor 114 that the patient's inspirationhas changed to expiration. If exhaling, for example, the data indicatesthat the upper threshold is met, thus signaling to microprocessor 114that the patient's expiration has changed to inspiration.

Based on the respiratory data, microprocessor 114 may adjust thepressure delivered to patient 101. For example, if microprocessor 114determines that the user is inhaling (e.g., based on the lower thresholdbeing met), then microprocessor 114 may send a control signal to blowercontroller 116 to set blower controller 116 to the therapy pressure. Inanother example, if microprocessor 114 determines that the user isexhaling (e.g., based on the upper threshold being met), thenmicroprocessor 114 may send a control signal to blower controller 116 toset blower controller 116 to the expiratory pressure.

In some embodiments, the therapy pressure and the expiratory pressuremay be set prior to operation. For example, in a bilevel PAP mode, thetherapy pressure and the expiratory pressure delivered to patient 101may be present by a medical professional. In some embodiments, such aswhen PAP device 10 is in a CPAP mode with expiratory relief, thecontinuous pressure (e.g., therapy pressure) may be preset by themedical pressure, and the expiratory pressure may be predefined asreductions in the therapy pressure and may be preset by a medicalprofessional or patient 101. For example, if the continuous pressure isset at 10 cm H₂O and a predefined reduction in pressure of 2 cm H₂O isset, the pressure exerted during exhalation may be 8 cm H₂O

Although blower controller 116 and microprocessor 114 are shown as aseparate components, those skilled in the art understand that blowercontroller 116 and microprocessor 114 can be a single computing device.

Microprocessor 114 may be configured to determine the upper thresholdand lower threshold through a variety of methods. In some embodiments,microprocessor 114 may calculate the thresholds based on a rate ofchange of the respiratory response curves. Microprocessor 114 may detectchanges in the slopes of the respiratory response curves. For example,the slopes of the respiratory response curves typically approach zero atthe end of expiration and inspiration. Using a specific example, theslope of a respiratory response curve at the end of expiration may bearound 0.02 cm H₂O/sec. If the slope changes negatively by, for example,0.1 cm H₂O/sec, such change may be used as a trigger for microprocessor114 to change the pressure delivered to patient 101. At the end ofinspiration, if the slope of the respiratory response curve changespositively by 0.1 cm H₂O/sec, such change can be used as a trigger formicroprocessor 114 to change the pressure delivered to patient 101.

In some embodiments, microprocessor 114 may calculate the thresholdsbased on a determined deviation from maximum pressure (e.g., upperthreshold) or pressure deviation from minimum pressure (e.g., lowerthreshold). For example, in some embodiments, the upper threshold may bepredefined as 0.5 cm H₂O above the maximum pressure or the therapypressure; the lower threshold may be predefined as 0.5 cm H₂O below theminimum pressure.

In some embodiments, microprocessor 114 may be configured to learn arespiratory pattern of patient 101. For example, as discussed above,second sensor 132 may be configured to monitor the pressure changeclosest to patient 101, while first sensor 130 may be configured tomonitor the pressure change within buffer chamber 110, so that thepressure supplied to patient 101 is constant. As those skilled in theart understand, there will be variability between the pressures measuredby first sensor 130 and second sensor 132. For example, the pressurereadings recorded by second sensor 132 may be more variable, given itsproximity to patient 101. To identify a respiratory pattern of patient101, microprocessor 114 may be configured to subtract the pressurereading of second sensor 132 from the pressure reading of first sensor130. Such process may eliminate any fluctuations in pressure attributedto blower 106. In this manner, microprocessor 114 may learn therespiratory pattern of the user.

For example, the pressure at first sensor 130 may vary by around +/−0.2cm H₂O, reflecting the control of blower 106. The pressure at secondsensor 132 may vary by around +/−0.7 cm H₂O, reflecting variation ofpatient 101, but also including the variation due to motor control ofblower 106. Accordingly, the instantaneous difference between pressurereadings at first sensor 130 and second sensor 132 may more accuratelyreflect the inspiratory pattern of patient 101.

FIG. 2A illustrates a buffer chamber 200, according to exampleembodiments. Buffer chamber 200 may be representative of an embodimentof buffer chamber 110. As shown, buffer chamber 200 may include a body202 defining an interior volume 201. Buffer chamber 200 may includefirst opening 204 and a second opening 205. First opening 204 may beconfigured to receive gas from gas manifold 108 via connector 112.Second opening 205 may be configured to deliver gas to patient deliverysystem 124 via patient connection port 122. Second sensor 132 may bepartially disposed in interior volume 201.

FIG. 2B illustrates a buffer chamber 220, according to exampleembodiments. Buffer chamber 220 may be representative of an embodimentof buffer chamber 110. As shown, buffer chamber 200 may include a body222 defining an interior volume 221. Buffer chamber 220 may includefirst opening 224 and a second opening 225. First opening 224 may beconfigured to receive gas from gas manifold 108 via connector 112.Second opening 225 may be configured to deliver gas to patient deliverysystem 124 via patient connection port 122. Second sensor 132 may bepartially disposed in interior volume 221.

As shown, buffer chamber 220 may further include a mechanism 226.Mechanism 226 may be representative of a flow restrictor or disruptor.Mechanism 226 may be used to provide backpressure to PAP device 100, asmeasured by second sensor 132. In the embodiments shown in FIG. 2B,mechanism 226 may be a single plate 228 with a plurality of gaspassthrough openings 230.

FIG. 2C illustrates a buffer chamber 240, according to exampleembodiments. Buffer chamber 240 may be representative of an embodimentof buffer chamber 110. As shown, buffer chamber 240 may include a body242 defining an interior volume 241. Buffer chamber 240 may includefirst opening 244 and a second opening 245. First opening 244 may beconfigured to receive gas from gas manifold 108 via connector 112.Second opening 245 may be configured to deliver gas to patient deliverysystem 124 via patient connection port 122. Second sensor 132 may bepartially disposed in interior volume 241.

As shown, buffer chamber 240 may further include a mechanism 246.Mechanism 246 may be representative of a flow restrictor or disruptor.Mechanism 246 may be used to provide backpressure to PAP device 100, asmeasured by second sensor 132. In the embodiments shown in FIG. 2C,mechanism 246 may be a cone 248 with a gas passthrough openings 250 atthe base of cone 248.

FIG. 2D illustrates a buffer chamber 260, according to exampleembodiments. Buffer chamber 260 may be representative of an embodimentof buffer chamber 110. As shown, buffer chamber 260 may include a body262 defining an interior volume 261. Buffer chamber 260 may includefirst opening 264 and a second opening 265. First opening 264 may beconfigured to receive gas from gas manifold 108 via connector 112.Second opening 265 may be configured to deliver gas to patient deliverysystem 124 via patient connection port 122. Second sensor 132 may bepartially disposed in interior volume 261.

As shown, buffer chamber 260 may further include a mechanism 266.Mechanism 266 may be representative of a flow restrictor or disruptor.Mechanism 266 may be used to provide backpressure to PAP device 100, asmeasured by second sensor 132. In the embodiments shown in FIG. 2D,mechanism 266 may be a single plate 268 that covers half of the gaspathway.

FIG. 3 is a chart 300 illustrating patient respiratory response 302measured by first sensor 130, according to example embodiments. FIG. 4is a chart illustrating patient respiratory response 402 measured bysecond sensor 132, according to example embodiments. As clear from acomparison of chart 300 to chart 400, the pressure as measured by secondsensor 132 is more variable than the pressure as measured by firstsensor 130. This is attributed to second sensor 132 being closer topatient 101 than first sensor 130.

FIG. 5 is a chart 500 illustrating portion 404 of chart 400 in moredetail, according to example embodiments. As shown in FIG. 4 , a portion404 of chart 400 is emphasized. Portion 404 may be referred to aspatient respiratory response curve 502. When determining whether a useris inhaling or exhaling, microprocessor 114 may determine if an upperthreshold 504 or lower threshold 506 is met.

Microprocessor 114 may calculate a first slope (S1) of respiratoryresponse curve 502 at the end of respiration. Microprocessor 114 maycalculate slope S1 over several seconds in real-time. Microprocessor 114may calculate a second slope (S2) of respiratory response curve 502 atthe end of respiration and after inspiration begins. Microprocessor 114can calculate second slope (S2) continuously, in real-time, and infractional seconds. Microprocessor 114 may calculate upper threshold 504in real-time and can immediately trigger a change in the pressure.

Microprocessor 114 may calculate a third slope (S3) of respiratoryresponse curve 502 at the end of inspiration. Microprocessor 114 maycalculate third slope (S3) over several seconds in real-time.Microprocessor 114 may calculate a second slope (S4) of respiratoryresponse curve 502 at the end of inspiration and after expirationbegins. Microprocessor 114 can calculate second slope (S4) continuously,in real-time, and in fractional seconds. Microprocessor 114 maycalculate lower threshold 506 in real-time and can immediately trigger achange in the pressure.

FIG. 6 is a block diagram illustrating PAP device 600, according toexample embodiments. PAP device 600 is substantially similar to PAPdevice 100. PAP device 600 illustrates a flow of data when during acalibration process.

As described above, the difference between the pressure at first sensor130 less the pressure at second sensor 132 more directly relates to thepatient's respiratory response. There is often a difference betweenpressures at second sensor 132 and first sensor 130. For example, ifsystem is closed, i.e., there is no gas flow, the pressure measured atfirst sensor 130 is the same as the pressure measured at second sensor132. As the airflow increases, the difference between the pressuresmeasured at first sensor 130 and second sensor 132 becomes greater. Toaccount for this, first sensor 130 may undergo a calibration process sothat the differences are eliminated or reduced.

FIG. 6 illustrates an example how first sensor 130 of PAP device 600 maybe calibrated, according to example embodiments. PAP device 600 may besubstantially similar to PAP device 100. During such process, output 602from first sensor 130 may be sent to the microprocessor 114. To begincalibration, microprocessor 114 may set the therapy setpoint to themaximum pressure of the PAP device 600.

In some embodiments, during calibration, PAP device 600 may be connectedto an adjustable valve 606. Valve 606 may be closed fully at the startof calibration so that there is no air flow through PAP device 600.Valve 606 may be incrementally opened. At each increment, microprocessor114 may record pressure readings from first sensor 130 and second sensor132. This process may continue until valve 606 is fully open. Tocalibrate sensor 130 and sensor 132, microprocessor 114 may correlatethe two pressures and output a calibrated control signal 608 to theblower controller 116. Although not shown, PAP device 600 may further beconnected to a flow meter.

For example, at each point of calibration, valve 606 may be openedincrementally. In some embodiments, there is a minimum of fourincrements at which sensor 130 and sensor 132 may record pressuremeasurements. At each increment, microprocessor 114 may receive twovalues: a first pressure as measured by sensor 132 (e.g., the desired ortherapy pressure) and a second pressure as measured by sensor 130 (e.g.,the blower control pressure). Because microprocessor 114 outputs thetherapy pressure to blower controller 116, it is beneficial that thepressure at first sensor 130 be “calibrated” to substantially the samepressure as that measured by second sensor 132. If, for example, thecorrelation between the pressure measured at second sensor 132 and thepressure measured at first sensor 130 was linear, then a linearcorrelation, e.g., y=mx+b, may be used, where x represents the pressureat second sensor 132 and y represents the calibrated pressure at firstsensor 130. For example, if m=1.005 and b=0, then, if the therapypressure as measured by second sensor 132 is set to be 10 cm H₂O, theset pressure output to blower controller 116 may be 10.05. Accordingly,at a high flow rate, second sensor 132 may read lower than the setpressure to blower controller 116 if not calibrated. To compensate forthis difference, the set pressure would need to be higher.

FIG. 7 is a flow diagram illustrating a method 700 of administeringtherapy with PAP device 100, according to example embodiments. Method700 may begin at step 702.

At step 702, microprocessor 114 may set the therapy pressure of PAPdevice 100. In some embodiments, the therapy pressure may be input tomicroprocessor 114 via a user interface associated with microprocessor114. In some embodiments, the therapy pressure may be input tomicroprocessor 114 via an external device (e.g., a mobile device ofpatient 101) over a wired or wireless connection (e.g., Bluetooth,ZigBee, Wifi, etc.). In some embodiments, the therapy pressure may beautomatically determined by microprocessor 114.

At step 704, microprocessor 114 may initialize PAP device 100 to thetherapy pressure for delivery to patient 101. For example,microprocessor 114 may provide a signal to blower controller 116 to seta speed of blower 106 to maintain the determined therapy pressure. Thesignal to blower controller 116 from microprocessor 114 may cause blowercontroller 116 to output a blower output signal to terminal block 118 tocontrol a speed of blower 106, such that blower 106 produces the therapypressure.

At step 706, microprocessor 114 may monitor responsive pressure based onfeedback from second sensor 132. For example, microprocessor 114 mayreceive real-time pressure readings from second sensor 132 as PAP device100 delivers the therapy pressure to patient 101. Microprocessor 114 mayanalyze the real-time pressure readings to determine when to adjust thepressure delivered to patient 101. For example, microprocessor 114 maydynamically adjust the pressure delivered to the patient 101 based on adetermination as to whether patient 101 is exhaling or inhaling.

At step 708, microprocessor 114 may determine whether patient 101 isabout to stop inhaling based on the monitored responsive pressure. Forexample, microprocessor 114 may receive respiratory data from secondsensor 132. In some embodiments, the respiratory data may berepresentative of a measure of pressure over time. Microprocessor 114may analyze the respiratory data to identify a lower threshold.

If, at step 708, microprocessor 114 determines that an inspiratorythreshold has been met (i.e., patient 101 has hit the lower threshold),then this may indicate to microprocessor 114 that the patient'sinspiration has changed or is about to change to expiration.Accordingly, at step 710, microprocessor 114 may change the pressure(e.g., lower the pressure) delivered to the user to the expirationpressure. In some embodiments, changing the pressure delivered to theuser may include microprocessor 114 sending a signal to blowercontroller 116 or block terminal block 118 to cause blower controller116 or block terminal block 118 to adjust to speed of blower 106 toachieve the expiration pressure.

If, however, at step 708, microprocessor 114 determines that patient 101is not about to stop inhaling, then, at step 712, microprocessor 114 maymaintain the pressure therapy.

At step 714, microprocessor 114 may determine whether patient 101 isabout to stop exhaling based on the monitored responsive pressure. Forexample, microprocessor 114 may receive respiratory data from secondsensor 132. In some embodiments, the respiratory data may berepresentative of a measure of pressure over time. Microprocessor 114may analyze the respiratory data to identify an upper threshold.

If, at step 714, microprocessor 114 determines that an expiratorythreshold has been met (i.e., patient 101 has hit the upper threshold),then this may indicate to microprocessor 114 that the patient'sexpiration has changed or is about to change to inspiration.Accordingly, at step 716, microprocessor 114 may change the pressuredelivered to the user to the therapy pressure. In some embodiments,changing the pressure delivered to the user may include microprocessor114 sending a signal to blower controller 116 or block terminal block118 to cause blower controller 116 or block terminal block 118 to adjustto speed of blower 106 to achieve the therapy pressure.

If, however, at step 714, microprocessor 114 determines that patient 101is not about to stop exhaling, then, at step 718, microprocessor 114 maymaintain the pressure therapy.

Such switching between therapy pressure and expiratory pressure maycontinue until therapy has concluded.

FIG. 8 is a flow diagram illustrating a method 800 of administeringtherapy with PAP device 100, according to example embodiments. Method800 may begin at step 802.

At step 802, blower controller 116 may monitor pressure in gas manifold108 based on feedback from first sensor 130. For example, microprocessor114 may receive real-time pressure readings from first sensor 130 as PAPdevice 100 delivers the therapy pressure to patient 101. Microprocessor114 may analyze the real-time pressure readings to determine when toadjust the pressure such that the current pressure setpoint ismaintained. For example, microprocessor 114 may dynamically adjust thespeed of blower 106, such that the pressure in gas manifold 108 remainsconsistent.

At step 804, blower controller 116 may determine whether the pressure ingas manifold 108 deviated at a threshold amount from the setpointpressure (e.g., therapy pressure, expiratory pressure, etc.) based onpressure readings from first sensor 130.

If, at step 804, blower controller 116 determines that the pressure ingas manifold 108 is consistent (e.g., the pressure does not deviate athreshold amount from the setpoint pressure), then at step 806 blowercontroller 116 may maintain the speed of blower 106. In other words,blower controller 116 may not adjust the speed of blower 106.

If, however, at step 804, blower controller 116 determines that thepressure in gas manifold 108 is not consistent (e.g., the pressure ingas manifold 108 has deviated a threshold amount from the setpointpressure), then at step 808 blower controller 116 may adjust the speedof blower 106 so that the setpoint pressure is once again achieved. Insome embodiments, controller 116 may send a blower controller outputsignal to terminal block 118 to adjust the speed of blower 106.

Such monitoring may continue until therapy has concluded.

FIG. 9A illustrates a system bus architecture of computing system 900,according to example embodiments. System 900 may be representative of atleast a portion of microprocessor 114 and/or blower controller 116. Oneor more components of system 900 may be in electrical communication witheach other using a bus 905. System 900 may include a processing unit(CPU or processor) 910 and a system bus 905 that couples various systemcomponents including the system memory 915, such as read only memory(ROM) 920 and random access memory (RAM) 925, to processor 910. System900 may include a cache of high-speed memory connected directly with, inclose proximity to, or integrated as part of processor 910. System 900may copy data from memory 915 and/or storage device 930 to cache 912 forquick access by processor 910. In this way, cache 912 may provide aperformance boost that avoids processor 910 delays while waiting fordata. These and other modules may control or be configured to controlprocessor 910 to perform various actions. Other system memory 915 may beavailable for use as well. Memory 915 may include multiple differenttypes of memory with different performance characteristics. Processor910 may include any general purpose processor and a hardware module orsoftware module, such as service 1 932, service 2 934, and service 3 936stored in storage device 930, configured to control processor 910 aswell as a special-purpose processor where software instructions areincorporated into the actual processor design. Processor 910 mayessentially be a completely self-contained computing system, containingmultiple cores or processors, a bus, memory controller, cache, etc. Amulti-core processor may be symmetric or asymmetric.

To enable user interaction with the computing system 900, an inputdevice 945 may represent any number of input mechanisms, such as amicrophone for speech, a touch-sensitive screen for gesture or graphicalinput, keyboard, mouse, motion input, speech and so forth. An outputdevice 935 may also be one or more of a number of output mechanismsknown to those of skill in the art. In some instances, multimodalsystems may enable a user to provide multiple types of input tocommunicate with computing system 900. Communications interface 940 maygenerally govern and manage the user input and system output. There isno restriction on operating on any particular hardware arrangement andtherefore the basic features here may easily be substituted for improvedhardware or firmware arrangements as they are developed.

Storage device 930 may be a non-volatile memory and may be a hard diskor other types of computer readable media which may store data that areaccessible by a computer, such as magnetic cassettes, flash memorycards, solid state memory devices, digital versatile disks, cartridges,random access memories (RAMs) 925, read only memory (ROM) 920, andhybrids thereof.

Storage device 930 may include services 932, 934, and 936 forcontrolling the processor 910. Other hardware or software modules arecontemplated. Storage device 930 may be connected to system bus 905. Inone aspect, a hardware module that performs a particular function mayinclude the software component stored in a computer-readable medium inconnection with the necessary hardware components, such as processor910, bus 905, output device 935 (e.g., display), and so forth, to carryout the function.

FIG. 9B illustrates a computer system 950 having a chipset architecturethat may represent at least a portion of microprocessor 114 and/orblower controller 116. Computer system 950 may be an example of computerhardware, software, and firmware that may be used to implement thedisclosed technology. System 950 may include a processor 955,representative of any number of physically and/or logically distinctresources capable of executing software, firmware, and hardwareconfigured to perform identified computations. Processor 955 maycommunicate with a chipset 960 that may control input to and output fromprocessor 955. In this example, chipset 960 outputs information tooutput 965, such as a display, and may read and write information tostorage device 970, which may include magnetic media, and solid statemedia, for example. Chipset 960 may also read data from and write datato storage device 975 (e.g., RAM). A bridge 980 for interfacing with avariety of user interface components 985 may be provided for interfacingwith chipset 960. Such user interface components 985 may include akeyboard, a microphone, touch detection and processing circuitry, apointing device, such as a mouse, and so on. In general, inputs tosystem 950 may come from any of a variety of sources, machine generatedand/or human generated.

Chipset 960 may also interface with one or more communication interfaces990 that may have different physical interfaces. Such communicationinterfaces may include interfaces for wired and wireless local areanetworks, for broadband wireless networks, as well as personal areanetworks. Some applications of the methods for generating, displaying,and using the GUI disclosed herein may include receiving ordereddatasets over the physical interface or be generated by the machineitself by processor 955 analyzing data stored in storage device 970 orstorage device 975. Further, the machine may receive inputs from a userthrough user interface components 985 and execute appropriate functions,such as browsing functions by interpreting these inputs using processor955.

It may be appreciated that example systems 900 and 950 may have morethan one processor 910 or be part of a group or cluster of computingdevices networked together to provide greater processing capability.

While the foregoing is directed to embodiments described herein, otherand further embodiments may be devised without departing from the basicscope thereof. For example, aspects of the present disclosure may beimplemented in hardware or software or a combination of hardware andsoftware. One embodiment described herein may be implemented as aprogram product for use with a computer system. The program(s) of theprogram product define functions of the embodiments (including themethods described herein) and can be contained on a variety ofcomputer-readable storage media. Illustrative computer-readable storagemedia include, but are not limited to: (i) non-writable storage media(e.g., read-only memory (ROM) devices within a computer, such as CD-ROMdisks readably by a CD-ROM drive, flash memory, ROM chips, or any typeof solid-state non-volatile memory) on which information is permanentlystored; and (ii) writable storage media (e.g., floppy disks within adiskette drive or hard-disk drive or any type of solid staterandom-access memory) on which alterable information is stored. Suchcomputer-readable storage media, when carrying computer-readableinstructions that direct the functions of the disclosed embodiments, areembodiments of the present disclosure.

It will be appreciated to those skilled in the art that the precedingexamples are exemplary and not limiting. It is intended that allpermutations, enhancements, equivalents, and improvements thereto areapparent to those skilled in the art upon a reading of the specificationand a study of the drawings are included within the true spirit andscope of the present disclosure. It is therefore intended that thefollowing appended claims include all such modifications, permutations,and equivalents as fall within the true spirit and scope of theseteachings.

1. A positive airway pressure device, comprising: a blower; a bufferchamber downstream of the blower, the buffer chamber configured toreceive gas generated by the blower and output the gas to a patient, thebuffer chamber comprising a mechanism configured to provide backpressureto the positive airway pressure device, wherein the mechanism is atleast one of: a single plate with a plurality of gas passthroughopenings formed therethrough, a cone with a gas passthrough openingformed at a base of the cone, or a single plate that covers half of agas pathway through the buffer chamber; a gas manifold fluidly couplingthe blower to the buffer chamber; a first sensor at least partiallydisposed in the gas manifold, the first sensor configured to measure afirst pressure in the gas manifold; a second sensor at least partiallydisposed in the buffer chamber, the second sensor configured to measurea second pressure in the buffer chamber; and a controller incommunication with the blower, the first sensor, and the second sensor,the controller configured to perform operations, comprising:initializing the blower to deliver a therapy pressure to the patientduring an inhale; receiving, from the second sensor, real-time pressurereadings while delivering therapy to the patient; analyzing thereal-time pressure readings to determine that the patient is about toswitch from the inhale to an exhale; and based on the analyzing, causingthe blower to deliver an expiratory pressure to the patient during theexhale, the expiratory pressure being a lower pressure than the therapypressure.
 2. The positive airway pressure device of claim 1, furthercomprising: receiving, from the first sensor, a gas manifold pressurereading during delivery of the expiratory pressure to the patient;determining, based on the gas manifold pressure reading, that aninternal pressure in the gas manifold has deviated a threshold amountfrom the expiratory pressure; and based on the determining, adjusting aspeed of the blower to maintain the expiratory pressure.
 3. The positiveairway pressure device of claim 1, further comprising: receiving, fromthe second sensor, additional real-time pressure readings whiledelivering the expiratory pressure to the patient; analyzing theadditional real-time pressure readings to determine that the patient isabout to switch from the exhale to a second inhale; and based on theanalyzing, causing the blower to deliver the therapy pressure to thepatient during the second inhale.
 4. The positive airway pressure deviceof claim 3, further comprising: receiving, from the first sensor, a gasmanifold pressure reading during delivery of the therapy pressure to thepatient; determining, based on the gas manifold pressure reading, thatan internal pressure in the gas manifold has deviated a threshold amountfrom the therapy pressure; and based on the determining, adjusting aspeed of the blower to maintain the therapy pressure.
 5. The positiveairway pressure device of claim 3, wherein analyzing the real-timepressure readings to determine that the patient is about to switch fromthe inhale to the exhale comprises: determining that a pressure readingfrom the second sensor has hit an upper threshold indicative of a switchbetween the exhale to the second inhale.
 6. The positive airway pressuredevice of claim 1, wherein analyzing the real-time pressure readings todetermine that the patient is about to switch from the inhale to theexhale comprises: determining that a pressure reading from the secondsensor has hit a lower threshold indicative of a switch between theinhale to the exhale. 7-10. (canceled)
 11. A method of deliveringtherapy to a patient using a positive airway pressure device, the methodcomprising: initializing, by a computing system, a blower of thepositive airway pressure device to deliver a therapy pressure to apatient during an inhale; receiving, by the computing system from asecond sensor positioned at least partially in a buffer chamber of thepositive airway pressure device, real-time pressure readings whiledelivering therapy to the patient; analyzing, by the computing system,the real-time pressure readings to determine that the patient is aboutto switch from the inhale to an exhale; based on the analyzing, causing,by the computing system, the blower to deliver an expiratory pressure tothe patient during the exhale, the expiratory pressure being a lowerpressure than the therapy pressure; receiving, by the computing systemfrom a first sensor positioned in a gas manifold upstream of the bufferchamber and downstream of the blower, a gas manifold pressure readingduring delivery of the expiratory pressure to the patient; determining,by the computing system, based on the gas manifold pressure reading,that an internal pressure in the gas manifold has deviated a thresholdamount from the expiratory pressure; and based on the determining,adjusting, by the computing system, a speed of the blower to maintainthe expiratory pressure.
 12. (canceled)
 13. The method of claim 11,further comprising: receiving, by the computing system from the secondsensor, additional real-time pressure readings while delivering theexpiratory pressure to the patient; analyzing, by the computing system,the additional real-time pressure readings to determine that the patientis about to switch from the exhale to a second inhale; and based on theanalyzing, causing, by the computing system, the blower to deliver thetherapy pressure to the patient during the second inhale.
 14. The methodof claim 13, further comprising: receiving, by the computing system fromthe first sensor positioned in the gas manifold upstream of the bufferchamber and downstream of the blower, a second gas manifold pressurereading during delivery of the therapy pressure to the patient;determining, by the computing system, based on the second gas manifoldpressure reading, that the internal pressure in the gas manifold hasdeviated the threshold amount from the therapy pressure; and based onthe determining, adjusting, by the computing system, the speed of theblower to maintain the therapy pressure.
 15. The method of claim 13,wherein analyzing, by the computing system, the real-time pressurereadings to determine that the patient is about to switch from theinhale to the exhale comprises: determining that a pressure reading fromthe second sensor has hit an upper threshold indicative of a switchbetween the exhale to the second inhale.
 16. The method of claim 11,wherein analyzing, by the computing system, the real-time pressurereadings to determine that the patient is about to switch from theinhale to the exhale comprises: determining that a pressure reading fromthe second sensor has hit a lower threshold indicative of a switchbetween the inhale to the exhale.
 17. The method of claim 11, furthercomprising: initiating, by the computing system, an offline calibrationprocess for the first sensor positioned in the gas manifold upstream ofthe buffer chamber and downstream of the blower, the offline calibrationprocess configured to reduce differences in readings between the firstsensor and the second sensor; recording, by the computing system, afirst plurality of pressure readings from the first sensor and a secondplurality of pressure readings from the second sensor, the firstplurality of pressure readings and the second plurality of pressurereadings based on a varying amount of pressure delivered to the positiveairway pressure device; correlating, by the computing system, the firstplurality of pressure readings with the second plurality of pressurereadings; and calibrating, by the computing system, the first sensorbased on the correlating.
 18. A positive airway pressure device,comprising: a blower; a buffer chamber downstream of the blower, thebuffer chamber configured to receive gas generated by the blower andoutput the gas to a patient; a gas manifold fluidly coupling the blowerto the buffer chamber; a first sensor at least partially disposed in thegas manifold, the first sensor configured to measure a first pressure inthe gas manifold; a second sensor at least partially disposed in thebuffer chamber, the second sensor configured to measure a secondpressure in the buffer chamber; and a controller in communication withthe blower, the first sensor, and the second sensor, the controllerconfigured to perform operations, comprising: initiating a calibrationprocess for the first sensor, the calibration process configured toreduce differences in readings between the first sensor and the secondsensor; recording a first plurality of pressure readings from the firstsensor and a second plurality of pressure readings from the secondsensor, the first plurality of pressure readings and the secondplurality of pressure readings based on a varying amount of pressuredelivered to the positive airway pressure device; correlating the firstplurality of pressure readings with the second plurality of pressurereadings; and calibrating the first sensor based on the correlating. 19.The positive airway pressure device of claim 18, wherein the positiveairway pressure device is coupled with an adjustable valve.
 20. Thepositive airway pressure device of claim 19, wherein recording the firstplurality of pressure readings from the first sensor and the secondplurality of pressure readings from the second sensor comprises:recording a first pressure reading from the first sensor and a secondpressure reading form the second sensor for each position of theadjustable valve between fully opened and fully closed.